基于等几何分析（IGA）的弹丸瞬态挤进过程理论研究与实验设计

The change of chamber structure has a great influence on the force state of the barrel for automatic weapons. Mechanics mechanism research of the forcing core which is the most demanding position of the chamber during the projectile engraving process is still in experimental stage. According to the transient engraving process which has high impact, high friction and large deformation on the projectile, this project targets the reduction of the transient stress of the forcing core, firstly an innovative dynamic experiment of the transient projectile engraving process will be designed based on really firing process. Then a high accuracy NURBS geometry characterization model of projectile and barrel will be established based on the Isogeometric Analysis (IGA). The IGA model of transient projectile engraving process which is validated by analyzing the contact analysis of friction and large deformation based on the NURBS geometry characterization model, combined with the high temperature and pressure due to the transient strong impact loads changing in time and space as the projectile moving forward will be established and confirmed by experiment. The variation of the forcing cone stress with varying parameters on different chamber structure will be researched and a primary design theory of forcing cone structure for the small arms will be formed. Furthermore, the numerical equation of the projectile engraving process considering engraving resistance will be established to optimize the forcing cone structure based on the Stochastic Response Surface Method (SRSM).The results of this study which have important theoretical significance and application value will reveal the mechanics mechanism during the process of projectile engraving, improve the life span of the small arm barrel and promote the theoretical level of the barrel weapon design of our country.

自动武器身管内膛结构变化对身管的受力影响极大，其中针对弹丸挤进过程身管内膛受力最为苛刻的坡膛处的力学机理研究仍处于探索阶段。本项目针对弹丸瞬态挤进这一高冲击、强摩擦和大变形过程，以缓解坡膛处瞬态受力为研究目标，首先创新设计基于真实射击过程的弹丸瞬态挤进过程动态测量实验；然后基于等几何分析方法建立精确的弹丸和身管的NURBS几何表征模型，分析基于NURBS几何的有摩擦、大变形的接触分析算法，结合随弹丸前进而时空演变的高温、高压瞬态强冲击载荷，建立弹丸瞬态挤进过程的等几何分析模型并进行验证；研究多个坡膛结构参数耦合变化时身管坡膛处瞬态受力的变化规律，形成初步的自动武器坡膛结构设计依据，在此基础上，建立包含挤进阻力的内弹道挤进过程方程组，基于随机响应面法优化坡膛结构。本项目成果对于弹丸挤进过程机理揭示，提高身管寿命，提升我国身管武器设计的理论水平具有重要的理论意义和军民应用价值。

本项目设计并搭建了基于真实射击过程的弹丸瞬态挤进过程高精度动态测量实验系统，针对不同内膛结构身管进行了实验测量，分别获得了原矩形膛线和圆切型膛线弹丸挤进过程阻力实验曲线，峰值分别为17000N和8800N；完成了基于Mathematica软件的等几何分析（IGA）建模编程，编制了5000余行代码，采用拟牛顿迭代算法实现了基于Mortar方法的拟牛顿改进的双通道计算，提高了等几何分析的效率；结合实验结果验证了弹丸瞬态挤进及沿膛运动过程有限元模型的可靠性，针对不同的内膛结构，有限元仿真结果和实验结果相比误差均在5%以内；研究了不同身管内膛结构对身管受力的影响，分析了弹丸挤进及沿膛运动过程中身管内壁不同部位随时空演变的瞬态受力的变化规律，结果表明圆切型膛线的受力最为缓和，五锥中间导转侧顶端的应力值最大，四锥小端截面作用在导转侧中点的正应力值最大；建立了不同寿命阶段弹/枪相互作用模型，研究了内膛损伤对完整内弹道过程的影响规律，结果表明随着射弹数的增加，内弹道过程最大膛压点在向身管尾部移动，轴向阻力的峰值向身管口部方向移动，内膛损伤会严重影响弹丸初始扰动和弹头出膛时表面形貌。